1. Priority Information
This application claims priority benefit under 35 U.S.C. § 119 to Japanese Patent Application No. 2003-376777, filed Nov. 6, 2003, the entire contents of which are hereby expressly incorporated by reference.
2. Field of the Invention
The present invention relates to a vehicle speed display device and, more particularly, to a speed display device that selects a speed value to display based on a plurality of detected speed values detected by a plurality of speed sensors of different types.
3. Description of the Related Art
A variety of devices that use different methods for detecting the speed of a moving vehicle, such as a boat, are known. For example, one device detects the moving (propulsion) speed of the boat using a radio wave signal from a global positioning system (GPS). Another device for detecting the speed of a boat is a paddle wheel type speed sensor, which has a paddle wheel that is rotated by the resistance of a water flow created when the boat is propelled. The moving speed of the boat can be detected by detecting the rotational speed of the paddle wheel. Another device for detecting the moving speed of a boat uses a picot tube.
Due to variations and errors rates in devices, different types of moving speed detection devices may detect different detected speed values for the same moving vehicle at the same time. In an attempt to make allowance for this fact, one existing speed display device includes a plurality of speed sensors that use different methods to detect the vehicle's moving speed, such as, for example, three different sensors, and a display that displays all of the speed values detected by the plurality of speed sensors. An operator of the boat or other vehicle can therefore see the various detected speed values of varying accuracies on the display.
Each of the sensors performs more accurately under different moving state conditions, such as at different speeds and/or at different levels of acceleration. Thus, when speed values of the boat are displayed on the display based on the detected speed values detected by the three speed sensors, the speed values often do not coincide with one another. Some of the detected speed values detected by the speed sensors may be close to the actual speed of the boat. It is, however, difficult for the operator to determine which of the displayed speed values is close to the actual speed value unless the operator is highly skilled. The interplay of effects of speed and acceleration on the accuracy of vehicle speed sensors is something that would be difficult for a normal operator of a vehicle to assess while maneuvering the vehicle. Thus, it is difficult in general for the operator to determine the accurate moving speed of the boat based on the displayed speed values, and maneuvering the boat or other vehicle may be more difficult and/or dangerous.